High-frequency heating system



L. D. M DERMAlD HIGH-FREQUENCY HEATING SYSTEM Aug. 15, 1950 4 Sheets-Sheet 1 Filed Nov. 2, 1946 Aug. 5, 1950 L. D. M DERMAlD 2,519,193

HIGH-FREQUENCY HEATING SYSTEM Filed Nov. 2, 1946 4 Sheets-Sheet 2 9 Rm 3; kph

Aug. 15, 1950 Filed Nov. 2, 1946 OSC L- D. M DERMAlD HIGH-FREQUENCY HEATING SYSTEM 4 Sheets-Sheet 4 fly 6 I7? ah /7Z0?" 70/ Ziaydfl Jfacfiermaz'a 5 WM ll M Patented Aug. l 1950 2,519,193 HIGH -FREQUEN CY HEATING SYSTEM Lloyd 1). MacDermaid,

to Operadio Manuf Charles, 111., a corpor St. Charles, 111., assignor acturing Company, St. ation of Illinois Application November 2, 1946, Serial No. 707,508

5 Claims.

This invention relates to an electrical apparatus and particularly to a machine for assembling into an integral unit a voice coil bobbin, diaphragm and spider for use in loud speakers.- The above assembly, as used in dynamic speakers, is adapted to operate in an annular air gap having a relatively small transverse dimension. Thus, in most instances, the air gap dimension is of the order of several thousandths of an inch. It is essential that the voice coil and bobbin assembly be uniform, strong and as thin as possible. The invention hereinafter described provides a machine for assembling a bobbin, spider and diaphragm into a unitary assembly. The machine utilizes high frequency currents for cementing materials to be assembled.

The invention in general provides machines for making the assembly in units of two, said two machines being operated in push-pull. Any

lack of symmetry in high frequency potentials will be eliminated and more uniform operation will result.

For a more complete description of the invention, reference will now be made to the drawings wherein Figure 1 is a top plan View of two assembly units. Figure 2 is a sectional elevation on line 2-2 of Figure 1 showing one of the units. Figure 3 isan end elevation of the two units. Figured is a detail of one of the insulating rings used in a unit. Figure 5 is a section on line 55 of Figure 4. Figure 6 is a circuit diagram of one system. Figure 7 is a circuit diagram of a modified system.

Inasmuch as all the units are similar in construction, a detailed description of only one will be given. Thus, base I0 is provided with tubular standard H having reduced end l2 adjustably disposed in a suitable aperture in base lil. Set screw M is provided to lock standard H in position. Standard H has threaded portion l8 and terminates in machined annular conical tip ll. Conical tip i! has fiat annular end l8. Standard H is provided with cylindrical tubular channel- 20, the upper portion of which is enlarged to form channel 2|. Channel 2| extends to the top of the standard.

Disposed around threaded portion [8 of; the standard is flanged ring 23 engaging threaded portion [6 and locked in position by lock nut 24. Flanged ring 23 has threaded portion 2'6 and machined supporting surface supported on bearing surface 3E. whose bottom surface 3i rests on annular supporting surface 27. Retainer ring 32 has threaded portion 33 cooperating with threaded portion of flange 23. Retainer ring 32 has collar portion adapted to cooperate with split ring 35 disposed in slot 36 in the lower portion of flange ring 36.

Flange ring 39 is made of any suitable metal and is preferably formed of bronze. However, the flange ring may be formed of brass, steel or any other desired material.

Flange ring 30 has a series of apertures 38 and another series of apertures 39, an aperture of one series alternating with an aperture of the other series. The peripheral portion of flange ring 38 is machined at 40 to provide an annular region upon which is bolted insulating ring 52. insulating ring 52 is preferably of glass, quarz or other material having low dielectric losses at radio frequencies. As is clearly evident in Figures 4 and 5, insulating ring 42 has a series of apertures 4 and another series of apertures 45, the two being so arranged that one alternates with the other. Apertures 45 have enlarged counter-sunk portions 5'! extending up from bot-- tom face 48 of ring 42. Apertures 44 have reduced portions 49 at the lower face of the ring, apertures 3'2 and 49 being similar to apertures 45 and 4? except that they are reversed.

As will be evident from Figure 2, apertures 38 in flange ring Jill are the same size as aperture 19 in ring 42, while apertures 39 in flange ring 39 are the same size as aperture ii in the ring. Apertures 28 of flange ring 33 and apertures 39 of flange ring 36 respectively register with the apertures 49 and 4! in the insulating ring.

Flange ring 30 has end portion 5a so sha l as to form a continuation of surface ll of standard ll. End portion to ter minates in annular portion 5| adjacent insulating ring 42.

Supported on insulating ring 42 is top ring 53 of any suitable metal such as bronze, brass or the like. Top ring 53 has machined annular surface 54 resting against the top face of insulating ring 42. Top ring 53 is provided with threaded blind recesses 55 registering with apertures 45 in the insulating ring.

21. Rotatably 2! is flange ring As will be evident from Figure 2, insulating ring 42 is rigidly bolted to flange ring 30 by bolts 56, while top ring 53 is bolted to the insulating ring by bolts 51.

Top ring has a plurality of annular step portions 50, 80 and ill. Each of these step portions forms an annular ring, and the lowest and innermost step portion SI is shaped to provide an upwardly and inwardly extending annular finger 53. surface 6e and taperin surface 65 defining the bottom portion of annular finger 03. It will be noted that'the inside diameter of annular finger 83 is somewhat greaterthan the diameter-"of cylindrical channel 2| for a reason to be ap- Top ring 53 has peripheral flange- 61 with a machined top supporting surface 88 parent later.

upon which is adapted to be disposed an annular insulating retaining member 'iil oi wood or the like. Retaining member. 'ie' 'nasy over- --be used.

hanging flange portion ll telescoping flange- Eli Telescoped within cylindrical;portion 2l is metallic sleeve member i3. Sleeve I3 has its bottom 14 somewhat short of the top end of inner wall 20 of standard H. Sleeve I3 has its top-end'IE substantially-in line with thltip. of: annular finger 63. Sleeve 13 fit'ssuificiently.tighta: withinenlargedgbore ii to remain in'positionibut I may be removed and replaced by another sleeve of difierent thickness. Sleeve I3 hasza predeteri-ir mined wall thickness to provide aniannular region I? between'the inside of sleeve '13 and center posts-i i9- disposed within-standard 'll andhavingre-a duced portion 80 actually defining the annular. region-I1; As -.will be apparent reducedportionilfi o'f the'central post e'xten'dsup-- wardlyior a substantial distance. above 'annularfinger 63.

Supported-from top end'fii of post 19 is a die assembly comprising annular-die .blocklZS having 4o' diaphra'gm 'are generallylformedzrg: cylindrical recess :84 formed itherein. Fitting..

smoothly into recess "84 is tapered die: member 85;..this comprising a generally cylindrical blockhaving cylindrical recess es formed thereingthis i I00 carrying voice coil IOI thereon. Bobbin I00 has its top end I02 rigidly fastened to inner edge I03 of spider I04. Spider I04 may take on a variety of forms as well known in the art and may consist of a true spider having a plurality of legs or may consist of an annular disc. Spider I04 is provided with annular mounting region I05. Upper portion I02 of bobbin I00 fits into and is rigidly attached to neck I01 of conical The bottom of top ring 53 has annular 1O diaphragm I08 having corrugated peripheral portion I09 and annular mounting portion I I0.

Bobbin I00, spider I04 and diaphragm I08 may beformed of any'suitable material; such asgpaper, fiber or the-like; and: have their overlapping parts I02, I03 and I01 cemented together. The cement used may be either thermo-setting or thermoplastic-- or-a combination of both. Thus, if a speaker is to be used under normal temperature conditionspthentthermoplastic cement alone may Ori'theother hand, if the speaker is to be used-underconditions where elevated temperatures areencountered, then a thermo-setting cement is necessary.

where athermo-setting cement is necessary, it is desirable to provide a mixture of both thermoplastic and'rthe'rmo'esetting. cements r- In that way; initial cementing- .due to athethermo-plastic cementiis secured:

Cements,2.ingenerahmave substantial dielectric a: losses tat. radio. frequencies and, 1 thus; areusetul in fdielectri'c heatingnx. A .thermoplastio .acement: ,2

available in-the'tradennderthe tradename-rVin-a yls'eal may be used, while .:a combination f-Of ither r mo-setting and thermoplastic .fcementc. is made;

iromu-Figure' 2, by -BakeliteflCor'poration and ssold. as: No; 116320. i:

Both of these-cements are-usefulToritheaspeaker .1. parts; since-the:dielectricllosses are concentrated therein rather than paper';gfiber, curedxlBakelit'e. or other material of which thesbobbin',.rspidenandrqr Bobbin I00 and=voice coil- I0l' are disp'osedw around sleeve" '13 'i'nithe -free: annularireg-ionl be tween parts Hand 64-. LSpiderJM is disposed; in position; so --that-- mounting -portion --l 05 r rests cylindrical recess having a sujficientlylarge diam-I; 5 step. l fl ith'xinner edg rportionurests me,

eter to pr'ovide an annular.clearance around re -1 duced' portion as of the central post. 1 The tapered top, is adapted 'to expand the neck of .the dia-:. phragm' cone so :that it willgo 'on the =outsidel:

of' the :voice coil bobbin as seenzin Figurev 8, Die a member 83 and tapered die member 05' have the bottom ends shaped to provide 'annularJ faces- 81: and;.88 respectively;'Annular face 88 is adaptedto be 'disposedvopposite top-II end 15' of sleeve 13' but i spaced at a slightadistance. .threfromlto'i provide gap190.

Die member 83 hasthreadedtop 9| :i'nto which is disposed stop bolt sii adjusted to any desired position by lock nut 83; lzStop bolt 92 isiadaptedx torest against topface'fil of the. top end of post o e -tandem.

19 and thus determine'ialimit to the position. at .which the entire'assembly may: drop.;t ..Cap 95 may be threaded over die portion 83 to enclose stop-bolt 92 and protect .the samezc Post To-thisend,-top ring 53 hasbo'ss -I-I5 formed thereonr said boss ext'end-iri'g f-rem -one side-of-- the Boss *I I 5 is provided with vertically I; disposed aperture H6 and asidewardly -disposed T9 is Vertically b Standard 5! and "as threaded'aperture -II'IF-Two-units -are"disposed be actuated by handle 91 disposed in the bottom A ofpost -;.'i9just above base' lll." Standai'dE- I'F ist: provided with clearance slot 98 in which handle 91' may move during vertical travel of post' lil.

It is apparent that, when handle-s'li i's raisedxm-ofthe opposing bosses;

upwardly, post 19 will be moved 'upwardlysito i raise the entire die assembly resting:on the top i end of the post.

The vibratory assembly portion of a speakeras shown 'in Figurelwith--bosses -Il5 andI 15 extending towardeach other. A U-Shaped-metal-L lic connectingmember lZIl-hasarmsJZI and I22 extending down through-apertures H 6 'andd I0. Connecting member: I 20 may be locked in any desired vertical-position by thumb screws-I23 and I 2 3 'disposed 'in thread ecl apertures II 7 and II Ie respectively.

Connecting members 2 0 is so dimensioned and: 1

shown in Figure 8 comprises-voice coil bobbin 5"shaped as to constitute inductance atsthe ire-w quencies used in the system. 1 ing k if a pair -of units may be vertical a justment (if, U; member rat Thi'sbonn ti d dfhiatna solid and may be a bent tube 7 as; has beenpoint d;si ti reyi v th ii electric heating units are operated in pairs. Reierring now to Figure 6, a diagrammatic showing of a system is disclosed. Here, oscillator I is connected through lines I3I and I32 to units L33 and I34. Units I33 and I34 are con-- nected by looped member I20. As shown in Figure 1, oscillator I30 may be disposed in any suitable casing and may have knob I36 for controlling the frequency. Handles I31 and I38 may control suitable contact members I39 and I40 for making contact with leads to the units. As shown in Figure 3, a pair of heating units are disposed on a circular table, only part of which is shown. This table is adapted to be moved intermittently past oscillator I30 so that successive pairs of heating units may be operated. Clamping members I3! and I38 are merely for purpose of providing a convenient detachable connection.

Referring now to Figure 7, a modified diagrammatic system is shown. In this system, oscillator i4 2 has output loop I43. Output loop I43 is inductively connected to loop I45 which is electrically one wave length long around the complete loop. Loop I45 has end I46 provided with meter I 47 connected between two spaced points at the loop end. Dielectric heating units I50 and I are connected substantially at the electrical midpoints of loop I45. Loop I45 has end i53. Tuning condenser I53 is connected across the loop between end I52 and dielectric heating units 556 and I5I. Condensers I54 and I55 are connected in series across the loop between end H53 and the dielectric heating units. The various condensers are provided for the purpose of insuring balance and symmetry. The condensers may be variable if desired to compensate for changing conditions.

In order to prevent destruction of any unit in case an arc occurs, it is possible to incorporate within the dielectric heating system a protective circuit described and claimed in the copending application of John McW. Stone, S. N. 578,67? filed February 19, 1945, now Patent 2,454,618 issued November 23, 1948. As applied to Figure 7, lead I58 may be connected to end I52 of the loop, while lead I59 may be connected through a radio frequency choke I60 to end I46 of the loop. A suitable high potential, either direct or alternating at a comparatively low frequency such as 60 cycles per second, may be applied to the two leads. It is evident that, if an arc occurs in either of units I50 or I5I, a low impedance connection is established and current will flow. In lead I59, for example, there may be connected relay I56 controlling the power input to oscillator I42.

The same protective system may be applied to the circuit shown in Figure 6.

What is claimed is:

1. For use in cementing an assembly of bobbin, spider and diaphragm all of insulating materials and used in a speaker, the inner edge por- 1 basses-0e nular earnaungregnnuawhich heat is to be generated, a dielectri type or heating system comprising a first iiietbldiiiiiiibr having an annular recess for accommodating tlie'Wobfiiii,

a second metallic annular die meinber ins'iilatin ly uppo ted,:w h s nestit a difir td 16" her, said second die member having the inne r edgeiorined as an annulafifi h I 4 iiti s'i fii f sins f is bobbiifndnn 'position'ior 'ceiiieriting witli th'e first two die members disposed on the same side of both diaphragm and spider and with the annular finger of said second die member extending to the cementing region, a third metallic die member having an annular portion, means for supporting said third die member on the other side of said spider and diaphragm with the annular portion disposed opposite to the annular finger but separated therefrom by the spider and diaphragm material, means for insulating said second and third die members from each other and means for applying high frequency potentials to said second and third die members to generate high frequency electric fields between the opposed annular die portions at the cementing region.

2. The structure of claim 1 wherein said first die member has a portion extending within the bobbin beyond the diaphragm and spider and wherein said third die member is supported from said last named portion, said second and third die members cooperating to maintain the parts at the cementing region in position during heatmg.

3. For use in cementing an assembly of bobbin, spider and diaphragm, all of insulating materials and used in a speaker, the contacting surfaces having cement and forming a cementing region in which heat is to be generated, a dielectric type of heater comprising the following: a metal sleeve and rod longitudinally movable in said sleeve, said rod and sleeve being shaped to provide an annular recess at one end of the sleeve for accommodating a bobbin, said rod extending beyond the sleeve end, an annular die member having its inner edge shaped to provide an annular finger, means for insulatingly supporting said die member rigidly with respect to said sleeve so that the annular finger is beyond the open sleeve end and around but spaced from said rod, means for supporting the diaphragm and spider on said die member so that the inner edges thereof contact the bobbin end for cementing, an additional die member supported from said rod and having an annular portion fitting against the inner edge portion of said diaphragm and spider to press the same against the bobbin, and means for applying high frequency potentials to said annular die member and additional die member to generate heat at said cementing regions, said rod and post being movable to release said cemented assembly clear after removal of said other die.

The structure according to claim 3 wherein a loose ring is provided for retaining the outer edge of the diaphragm against said annular die member, said post and sleeve normally being vertical with said ring member resting on the outer edge of said diaphragm by gravity.

5. A pair of structures according to claim 3 and a U-shaped connector between said strucment at themeeting surfaces to provide an sa ture with said, struqfiures bein g connected 1:; i

tlal I RE N E CITED file of :this patent I UNITED STATES PATENTS Nuihbgp Name. Date 1,550,651Q Charter, Aug. 18,1925 2, 1 09,323 'j S mith. Feb; 22, 1933 Number 

